GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - 5M7A52H4R_07U7T7J

The passage mentions which of the following as an effect of bird plumage? A. It contributes to a bird's ability to fly. B. It hides the inner workings of birds. C. It contributes to the structural soundness of birds.